TITLE: GCN CIRCULAR NUMBER: 16061 SUBJECT: GRB 140331A: Swift/UVOT Upper Limits DATE: 14/03/31 18:41:14 GMT FROM: Mike Siegel at PSU/Swift MOC M. H. Siegel (PSU) and B.-B. Zhang (UAH) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 140331A 394 s after the BAT trigger (Zhang et al., GCN Circ. 16049). No optical afterglow consistent with either the enhanced XRT position (Beardmore et al. GCN Circ. 16052) or the RATIR detection (Littlejohns et al. GCN Circ. 16050) is detected in the initial UVOT exposures. Preliminary 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first finding chart (FC) exposure and subsequent exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag white_FC 394 543 147 >21.1 white 394 8016 764 >21.9 v 550 7092 568 >19.7 b 649 7912 568 >20.8 u 624 7707 568 >21.1 w1 600 7502 563 >21.1 m2 575 7297 529 >20.5 w2 700 6887 352 >21.4 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.05 in the direction of the burst (Schlegel et al. 1998).